<!DOCTYPE html>
<html>
	<head>
		<meta charset="utf-8">
		<title></title>
	</head>
	<body>
	</body>
</html>
<script type="text/javascript">
	let arr = [1,2,3,4,5,4,3,2,1];
	// 数组去重
	let result = [...new Set(arr)]
	console.log(result)
	// 交集
	let arr2 =[4,5,6,5,6];
	let result2 = [...new Set(arr)].filter(item =>{
		let s2 = new Set(arr2);
		if(s2.has(item)){
			return true;
		}else{
			return false;
		}
	})
	console.log(result2)
	// 并集
	let result3 = [...new Set([...arr,...arr2])]
	console.log(result3)
	// 差集
	let diff = [...new Set(arr)].filter(item => !(new Set(arr2).has(item)));
	console.log(diff)
</script>